Britain's ambassador to Israel has angered its government by describing the Palestinian territories as "the largest detention camp in the world".

Sherard Cowper-Coles accused soldiers of humiliating and harassing civilians. He put his complaints to Maj-Gen Amos Gilad, the officer in charge of the welfare of Palestinians under occupation, after a tour of the West Bank which he is said to have found shocking.

After his comments were leaked to the press yesterday, a senior Israeli official said: "The ambassador has forgotten that the British mandate is over. He went too far."

British officials said the criticisms were co-ordinated with Whitehall after Gen Gilad visited London, where he was asked to explain why 3.5 million Palestinians were effectively locked up.

Although Israel has directed its anger at Mr Cowper-Coles, his criticism is part of an Anglo-American campaign.

Last week the American ambassador, Dan Kurtzer, delivered a letter to Ariel Sharon, the prime minister, calling for more freedom of movement for the Palestinians and an end to the killing of civilians by the army.

Mr Cowper-Coles said: "This conversation was part of a private dialogue between friends. We do not publicly lecture our Israeli friends. We do not believe in megaphone diplomacy."

The ambassador is seen as a sympathetic figure in Israel, thanks to his troubling to learn Hebrew. Last Sunday he appeared on a hard-hitting satirical television programme, arriving at the studio in a London taxi, carrying a rolled umbrella and wearing a trilby.